This study is designed to further study the safety and efficacy of orally administered SP-303 in patients with AIDS. Prior studies withis agent have shown some reduction in stool volume in patients with travellerUs diarrhea. This study will include HIV positive men and women 18 years and older with a confirmed stool volume at screening of 300 grams. Patients will be hospitalized in the GCRC for one day of screening and six days of treatment. Responders to treatment (identified as having a 50% reduction in stool volume from screening) will continue on their initial therapy for three additional weeks.